Process of separating sodium and potassium salts.



UNITED STATES PA CENT OFFICE.

HARRY r. BASSETT, 0F BALTIMORE, MARYLAND, ASSIGNOR TO: THE SP R CHEMICAL COMPANY, OF BALTIMORE, MARYLAND, A= CORPORATION OF MARYLAND.

PROCESS OF SEPARATING SODIUM AND POTASSIUM SALTS.

No Drawing.

To all whom it may concern.

Be it known that I, HARRY P. BASSETT, a citizen of the United States, residing at Baltimore, State of Maryland, have invented certain new and useful Improvements in Processes of Separating Sodium and Pot-assium Salts, of which the following is a specification.

This invention relates to the separation of potassium and sodium salts and has particular reference to a novel process of economically and readily separating potassium from sodium in a solution in which the potassium and sodium are present in the form of sulfates.

The process has particular adaptability to the separation of potassium in a process of recovering potassium from feldspar hereinafter set forth, but is adapted for use wherever potassium is to be separated from sodium where the said metals exist in the form of sulfates and itis to be understood that the invention is not specifically restricted to the recovery of potassium in feldspar treatment.

Heretofore great difficulty has been encountered in the separation of potassium from sodium where the metals exist in the form of sulfates. Now I have discovered that if sodium chlorid is added to a solution of potassium sulfate and sodium sulfate and the solution maintained at an elevated temperature the potassium can be recovered readily and economically by merely withdrawing the sodium sulfate crystals as formed and that the process can be carried on continuously, the solution under treat ment being added to the crystallizing tank as the solution becomes weak in sodium salt, and the sodium sulfate, in crystalline form, withdrawn either continuously or intermittently as the crystals form.

In my process of recovering potash from feldspar in which my new separation treatment is advantageously employed Ipreferably grind feldspar to a degree of fineness which will permitit to pass through a 40 to mesh sieve. I then mix" therewith sodium acid sulfate and sodium chlorid in approximately the following proportions: feldspar 5 parts by weight, sodium acid sulfate 5 parts by weight, sodium chlorid 1.8 parts by weight. The mixture is heated to preferably about 700 C. and the fused mass dumped whileghotintmwater until the solu- Specification of Letters Patent. Pate ted Mar. 24., 1914. Application filed September 7, 1911. Serial No. 648,008.

tion of the salts is approximately concentrated. The solution is separated by decantation or otherwise from the insoluble residue and there is then added to the soluing added as the solution becomes depleted of the sodium salts.

The withdrawn sodium sulfate is in practice, raked from the crystallizing tank into a second tank containing concentrated sodium sulfate solution in Water, which solution is preferably maintained at the same temperature as the solution in the first tank and from this second tank the purified sodium sulfate crystals are raked as formed. Where it is desired to obtain the sodium sulfate crystals in very pure form I employ a third ank containing concentrated sodium sulfate solution and into this'the crystals of sodium sulfate are raked from the second crystallizing tank. This third tank is maintained at the same temperature as the .first tank. The crystals after passing through the third tank are almost ehtirely free from contamination by other salts and are practically chemically pure. After the crystallization has been carried on in the first tank for a fewhours, the contents of this tank, which have gradually become richer-n1 potassiumsalt, will contain a content of potassium chlorid which is approximately 80 percent. by weight lof the salt present in such tank. This residue is drawn off andeva'pora'ted to dryness and is then ready for use or sale, 80 per cent. potassium chlorid being standard in t-he fertilizer" and powder industries.

I have found that some measure of success can be obtained by employing sodium nitrate in place of sodium chlorid in the practice of my process, in which case crystals of sodium sulfate are obtained. I have also found that an approximately concentrated 'solutionlof sodium chlorid can be employed il o 1 I I gredients it isto be'u-nderstood that the pro portions may be widely varied While I have describedgin detail'thepreferred practice of my process and theiproportions in which I prefer to mix myim spirit of my invention and that chemica equivalents as hereinbefore referredto 'ma be resorted to.

Having thus describedmy inventioni-jl claim y a v v 1. The herein described process which consists inadding sodium chlorid' to a solution of sodium sulfate and potassium sulfate, crystallizing a portion of the salt in solution, and separating the crystals: from) the mother liquor.

2. The herein described process which consists in adding sodium chlorid to a solu tion of sodium sulfate and potassium-sulfate, heating the solution until crystals form therein, and separating'ethe crystals from the mother li nor.

3. The herein escribed process which consists in adding sodium chlorid to a sub:

stantially saturated solution of sodium sul jrom. Tani-4'. The herein described process which consists in adding sodium ohlorid to a subs'tantially saturatedrsolutiontof"Sodium sulfate and potassium sulfate, cnyst'allizing a portion of the salt in solution,- withdrawing tliecrystals formed into a'substantially saturated solution of sodium sulfate 'and separating the crystals therefrom.

' 5 1Thel1erein described process whicl Iconsist-sinadding sodium chlorid to a substantially saturated solution of'sodiumlsul fate and potassium sulfate, maintaining-the solution at a temperature of from 50. C. to; "107 (1, withdrawingathe sodium salt crystals formed therein into a substantially saturated solution of sodium-'sulfate, maintaining. the last named solution at approximately from 60 C. to 107 C. and with drawing the crystals from the last named solution.

In testimony whereof I aflix my signature .in presence of two Witnesses.

HARRY P. BASSETT. Witnesses: I J Anus-K. P. WILKINSON,

, ALLAN HERBERT FISHER.

' Copies o! this patent may be obtained for five cents each; by addressingthe Commissioner -01 Pram Washlngtomhfl." 

